It took one visit to Yellowstone National Park for Mike Skelton, 60, to decide that he should move closer.

But as trash started to pile up in the park during the partial federal government shutdown, Mr. Skelton, who moved to Gardiner, Mont., from Dallas in 2015, felt he could not sit idly by. So he assembled a cleanup crew — “local area residents turned gardeners,” he said.

“We all live here,” said Mr. Skelton, who runs a sightseeing company providing wildlife and scenic park tours. “When it gets down to it, it is our park and it belongs to all of us in this country.”

“All of these National Park Service people are unable to do their job through no fault of their own,” Mr. Skelton said.

Last Saturday, 15 people showed up in Yellowstone to clean with him, Mr. Skelton said, but then a local businessman posted about the effort on Facebook and about 40 people showed up on Sunday.

They pulled trash out of the bathrooms, swept the floors, cleaned the toilets and replaced bottles of hand sanitizer. Some volunteers brought supplies from home or bought them along the way, he said.

“It is a very special place,” Mr. Skelton said. “I come in through the same gate every time and there is always something different to see.”

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Dozens of volunteers with the association, a Maryland-based organization that regularly organizes community service cleaning efforts across the country, were mobilized for cleaning efforts at parks around the country.CreditAhmadiyya Muslim Youth Association

“This is business as usual for us, but it is especially important in a time like this,” Mr. Bhatti said.

Zakaria Sayed, 29, who volunteered at Joshua Tree, said he had never been a “camping person,” but after he got married in 2014, he and his wife camped at the park many times.

Like other volunteers, he feels a personal connection to the park. “It was more sentimental to me to do what I can,” he said.

The cleanup, he said, was not “as awful” as he thought it would be.

“We thought it would be a disaster zone, but it was a lot better than expected,” he said.

A version of this article appears in print on , on Page A15 of the New York edition with the headline: ‘It Belongs to All of Us’: Volunteers Are Helping Keep National Parks Clean. Order Reprints | Today’s Paper | Subscribe